I wouldn't recommed it.
You would be placing added stress to the area of the body just above the mount that you place your spacer. The body is designed for a certain size bushing when attached to the frame. If you increase the size the same all the way around(ie 3" bl) then you have no problem. If the changes are not the same and you tighten down those body mounting bolts, you are essentailly bending the body to make it fit. Now, I'm not sure that a 1/4 of an inch is that big a deal, but you would be stressing the welds at your firewall, a pillar, rocker.
I just completed the lift on my 93. 3" BL, Skyjacker coils up front and WAR153 shackles in the rear. If have 32's and have only very minimal rubbing on rocker mouldings occassionally in the front. 33's would have caused necessary trimming or possible the same problems you're having now.
Good Luck...........